1. Field of the Invention
This invention pertains to electrical contacts and connectors made of metal-filled or carbon-filled resilient elastomers molded on or bonded to electrically conductive substrates and particularly to electrical connectors having a plurality of elastomeric contacts in a predetermined arrangement.
2. Description of the Prior Art
Electrical connectors having mechanical metal contacts which mate in some fashion to provide a continuous electrical path often provide for some relative motion between the mating contacts to effect the wiping action, thus ensuring proper connection. Where a plurality of such contacts are positioned in an electrically insulative holder or frame of sorts, some relative motion between the contacts is also generally provided to ensure proper alignment with the mating contacts. If a large number of contacts are so situated in a single holder or frame for simultaneous contact or where repeated making and breaking of the contacts is experienced, misalignment, wear, bending, shorting and other types of circuit failure are commonly experienced. Metal contacts have the additional difficulties of being generally difficult to reproduceably fabricate and subject to fatigue when under continuous use.
Any wiping action abrades the contact surfaces by removing plating and damaging soft conductors such as indium oxide and tin oxide. Metal-pressure contacts often become misaligned due to shock and vibration.
Where a permanent or semipermanent electrical connection is desired, but where soldering is impossible or undesirable, metal to metal contacts experience surface abrasion due to the wiping action of the initial contact which in time is subject to corrosion and increased contact resistance. The actual contacting area of a metal to metal contact is typically less than one-thousandth of the total surface area of the metal contact. Moisture or other hostile atmosphere can then migrate between the contact surfaces and rapidly deteriorate the quality of the metallic joint.
To overcome these problems, interconnector frames carrying conductive elastomeric contacts have been proposed to interface between two conductors or terminals. Examples are to be found in U.S. Pat. Nos. 3,648,002 and 3,680,037. The interconnectors add additional weight, take up usable space and increase lead length and circuit resistance. Another patent of general interest in this area is U.S. Pat. No. 3,509,296.
The composition of conductive elastomers which can be used in contacts according to this invention may be found in U.S. Pat. Nos. 3,140,342; 3,412,043 and 3,609,104, as well as others.